The Supreme Court declined to hear an appeal Tuesday from Arizona Sheriff Joseph Arpaio in a case challenging the president’s executive actions on immigration. Arpaio, an outspoken lawman, had argued that Obama’s measures to shield millions of illegal immigrants from deportation harmed him because those spared would commit crimes in Maricopa County and as sheriff he would be forced to spend more money policing the county and running its jails. In August, the U.S. Court of Appeals for the D.C. circuit affirmed a lower court’s December decision to dismiss the case for lack of legal standing. The D.C. Circuit Court…

Humanity is at risk from a series of dangers of our own making, according to Prof Stephen Hawking. Nuclear war, global warming and genetically-engineered viruses are among the scenarios he singles out. And he says that further progress in science and technology will create “new ways things can go wrong”. Prof Hawking is giving this year’s BBC Reith Lectures, which explore research into black holes, and his warning came in answer to audience questions. He says that assuming humanity eventually establishes colonies on other worlds, it will be able to survive. “Although the chance of a disaster to planet Earth…